"Bioreactor dome" and drug cocktail enables frog to regrow lost leg

Researchers have enabled an African clawed frog to regrow a missing leg using a drug cocktail swirling around the animal's stump within a "silicone wearable bioreactor dome." Even the name of the technology—"bioreactor dome"—sounds like something from a superhero comic. According to the Tufts and Harvard University scientists, the drugs were responsible for tamping down inflammation, inhibiting the production of collagen which would lead to scarring, and encouraging the new growth of nerve fibers, blood vessels, and muscle." (The image above is a normal specimen, not one with regenerated limbs.) From Tufts:

The researchers observed dramatic growth of tissue in many of the treated frogs, re-creating an almost fully functional leg. The new limbs had bone structure extended with features similar to a natural limb's bone structure, a richer complement of internal tissues, including neurons, and several "toes" grew from the end of the limb, although without the support of underlying bone[…]

The regrown limb moved and responded to stimuli such as a touch from a stiff fiber, and the frogs were able to make use of it for swimming through water, moving much like a normal frog would.

The five-drug cocktail represents a significant milestone toward the restoration of fully functional frog limbs and suggests further exploration of drug and growth factor combinations could lead to regrown limbs that are even more functionally complete, with normal digits, webbing, and more detailed skeletal and muscular features.

"We'll be testing how this treatment could apply to mammals next," said corresponding author Michael Levin, Vannevar Bush Professor of Biology in the School of Arts and Sciences, of the Allen Discovery Center at Tufts, and associate faculty member of [Harvard's] Wyss Institute.

"Acute multidrug delivery via a wearable bioreactor facilitates long-term limb regeneration and functional recovery in adult Xenopus laevis" (ScienceAdvances)

"Using the BioDome cap in the first 24 hours helps mimic an amniotic-like environment which, along with the right drugs, allows the rebuilding process to proceed without the interference of scar tissue," says researcher David Kaplan. (image: Nirosha Murugan/Tufts)

top image: Brian Gratwicke – FlickrXenopus laevis (CC BY 2.0)